From 62917dfec9603df43b1fb937d3c7ca55cad4f75d Mon Sep 17 00:00:00 2001
From: 4am <a2_4am@sent.com>
Date: Fri, 10 Nov 2017 13:38:31 -0500
Subject: [PATCH] enable address checksum verification by default to simplify
 code and so converted DOS 3.2 disks get it

---
 src/mods/universalrwts.a | 17 ++++++++---------
 src/passport.a           |  6 +-----
 src/rwts.a               |  3 ---
 src/strings/en.a         |  2 +-
 4 files changed, 10 insertions(+), 18 deletions(-)

diff --git a/src/mods/universalrwts.a b/src/mods/universalrwts.a
index 69ecc42..7879b38 100644
--- a/src/mods/universalrwts.a
+++ b/src/mods/universalrwts.a
@@ -6,20 +6,19 @@
 ;-------------------------------
 ; Universal RWTS
 ; a modified DOS 3.3-style RWTS that reads 16-sector (6-and-2 encoded) disks
-; - address prologue "D4 AA 96" or "D5 AA 96"
+; - address prologue $D4 $AA $96 or $D5 $AA $96
+; - verifies address field checksum
 ; - any address epilogue
-; - data prologue "D5 AA AD"
+; - data prologue $D5 $AA $AD
+; - verifies data field checksum
 ; - any data epilogue
-;
-; It verifies the data field checksum byte, but it ignores the address field
-; checksum. It waits longer than a normal RWTS to find an address prologue --
-; long enough that it will find the prologue even if there is only one sector
-; on a track.
+; - waits longer than a normal RWTS to find an address prologue (long enough
+;   that it will find the prologue even if there is only one sector on a track)
 ;
 ; It must be loaded at $B800. It uses the standard RWTS entry point at $BD00.
 ;
 ; Write support has been disabled. Any attempt to pass $02 or $04 RWTS commands
-; will crash.
+; will crash. See note below on how to re-enable.
 ;-------------------------------
 
 universalrwts
@@ -47,7 +46,7 @@ universalrwts
          !byte $8C,$C0,$10,$FB,$4A,$C9,$6A,$D0,$EF,$BD,$8C,$C0,$10,$FB,$C9,$AA
          !byte $D0,$F2,$BD,$8C,$C0,$10,$FB,$C9,$96,$D0,$E7,$A0,$03,$A9,$00,$85
          !byte $27,$BD,$8C,$C0,$10,$FB,$2A,$85,$26,$BD,$8C,$C0,$10,$FB,$25,$26
-         !byte $99,$2C,$00,$45,$27,$88,$10,$E7,$A8,$D0,$00,$BD,$8C,$C0,$10,$FB
+         !byte $99,$2C,$00,$45,$27,$88,$10,$E7,$A8,$D0,$B7,$BD,$8C,$C0,$10,$FB
          !byte $C9,$00,$D0,$00,$EA,$BD,$8C,$C0,$10,$FB,$C9,$00,$D0,$00,$18,$60
          !byte $86,$2B,$85,$2A,$CD,$78,$04,$F0,$53,$A9,$00,$85,$26,$AD,$78,$04
          !byte $85,$27,$38,$E5,$2A,$F0,$33,$B0,$07,$49,$FF,$EE,$78,$04,$90,$05
diff --git a/src/passport.a b/src/passport.a
index 6d9bcdb..ecca708 100755
--- a/src/passport.a
+++ b/src/passport.a
@@ -244,7 +244,6 @@ Action
          jsr   CreateRAMFile
 +        jsr   ResetProgress
          jsr   InitSectorMap
-         jsr   CopyUniversal
          lda   #FALSE
          sta   gTriedUniv
          sta   gSaidWriting
@@ -265,6 +264,7 @@ Action
          sta   TEXTTOP
          lda   #s_reading
          jsr   PrintByID
+         jsr   CopyUniversal
          jsr   IgnoreAddressChecksum
          jsr   ReadSector
          bcc   +
@@ -485,10 +485,6 @@ StartWithUniv
 ; note: execution falls through here
 
 CopyUniversal
-         lda   #>EnforceAddressChecksum-1
-         pha
-         lda   #<EnforceAddressChecksum-1
-         pha
          lda   #$B8
 CopyUniversalAnywhere
          sta   universalrwts
diff --git a/src/rwts.a b/src/rwts.a
index 386fd36..e3ae806 100755
--- a/src/rwts.a
+++ b/src/rwts.a
@@ -106,9 +106,6 @@ PreReadSector
 
 IgnoreAddressChecksum
          lda   #$00
-         !byte $2C        ; hide next LDA
-EnforceAddressChecksum
-         lda   #$B7
          sta   $B98A
          rts
 
diff --git a/src/strings/en.a b/src/strings/en.a
index 2485489..eadf0b4 100755
--- a/src/strings/en.a
+++ b/src/strings/en.a
@@ -134,7 +134,7 @@ StringTable
 ; can be set directly before calling PrintByID.
 ;
 .header
-         !text "Passport by 4am               2017-11-08",$00
+         !text "Passport by 4am               2017-11-10",$00
 .mainmenu
          !text "________________________________________",$8D,$8D,$8D,$8D,$8D,$8D,$8D
          !text "              "